The Upholstery Forum

I came by Singer 31-15 and I'm trying to get it tuned up to do upholstery. I'm working on a motorcycle seat made of vinyl. There's a quilted seat pad with a skirt piece around it. I'm trying to run 207 sized nylon thread for the quilting stitching. I ran a 23 size needle in the quilting area and it went fine. I got into to trouble with thread shredding and long loops in the top thread while stitching the skirt section on, especially where the vinyl stacked up to 5 layers. I tried going to a 25 needle and it solves my tension/thread shredding problem in the thick area but the 25 needle really works my machine. I have some 24 sized needles on order to see if those will work without working the machine too much. Any other tricks of the trade I should try before I give up on the 207 thread or am I wasting my time trying?

I should mention I've got an alternate feed dog and needle plate for the 25 needle that's drilled out in the needle area to provide a bit more clearance. I should maybe trying that dog/plate with the 23 needle?

Looks good but here is a question for you? Why the 207 thread? Why not dial it in with tx138 and have a classic diamond seat like the motorcycle seats were. The skirt piece did it require any TOP stitching? If not I would just seam it up with 69 or 92 thread. There are some good techinicians on here that will answers those ?'s

I could do that but I want the top stitch to really stand out. The bike has a black frame and red tank and side covers so the red stitch ties in with the red tank.

Here's the seat. First pic is a finished cover with a 92 top stitch using an old Bernina machine. Second pic is the latest attempt with 207 top stitch on the Singer 31-15 using a 23 sized needle. It actually looks pretty good except for one area in the skirt stitching where I had to rip it out twice because the thread shredded on me. 23 needle pokes some pretty good holes and making 3 passes doesn't help.

I'm still thinking about taking another run at if I can get a needle and machine set up worked out in practice pieces.

Why so many layers? From what I’m seeing if I’m seeing it right. The most you should have is 3. 5 layers adds a bit of resistance to machines and may also be the issue.

There were 5 doing the top stitch around the skirt where the seam in the skirt is. I could probably trim the seam before the top stitch and save a layer.

I guess I’m thinking the first layer of black for the insert diamond stitch. Then sew the skirting to that and then flip for a top stitch. Making 3 layers. 4 if you count the foam for the diamond stitch. But I would trim the foam close to the stitch after you sew the skirting to the insert and before you do your stop stitch around the skirting. I’m not saying the layers are the cause of the issue. But less will make it easier.

Is the 23 needle new? Maybe it’s the needle. May have a burr or is a bit worn out. I wish I knew more about machine mechanics to help. Also could be inconsistency with tension. Sometimes too tight others too loose?

I thinks it coll wanting to throw the stitch color from the seat to the tank but if things dont work out with the thread drop back to your 92 and use tank color vinyl for the insert.

@sandmanred What size thread are you using in the bobbin?

The 23 was brand new as well as the 25 sized needle. I got my 24 sized needles and had success going through as many as 5 layers of the vinyl in the pics and 1 layer of foam without breaking or shredding the thread with the 207 sized thread.

I used the same thread in the bobbin as the top. I've tried a size smaller in the bobbin but it seems to get pulled up to the finished side very easily so I quit trying.

Thanks for the suggestions!

You should use 92 in the bobbin, turn up the bobbin tension and loosen the top tension a little bit. This should solve your problems.

also increase your stitch length. with the thicker thread it looks better with longer stitches

Been a long time but I agree. I was maxed out on stitch length (about 5/inch) until recently when I modified the machine a bit to stretch out the stitch. I looked at modifying one of the links in the drop feed mechanism to lengthen it but that looked too complicated. Then I tried opening up the stitch length adjustment slot. I was able to get up to almost 4 stitches per inch from 5 by doing this. I was careful to listen and look for any interference in the machine as I stretched it out and I'm right on the edge but it still runs smooth. If I had gone any farther I start to hear an interference somewhere in the machine. I'm going to try the 207 again on another project soon.

Thanks for the update!

Here a shop stool seat with 207 thread. I was a little careless on the foam and batting as it's an old stool but I was happy with the stitching and appearance of the top stitch. It's a stitch length of about 4.25 stitches per inch.

Looks awesome! Really cool stitch design!

Thank for your help. I did also try 138 in the bobbin and it worked just fine. Even one size smaller goes a lot farther than the 207.

Hello my Friend , IAM sam from France, sorry for my english.
First i'am verry impress of your work on the motocycle Seat !!
I am a newbie i have made a Seat for my sporster Harley with an old sewing family brother but not happy..the power IS not good for that
I Can a have a singer 31k15 like you for a Small Price..
I have questions for you
it IS ok for vinyl and 20 mm foam?
Have you modify the singer 31k15 like a walking foot or a roller?
Can you Help me ?
I love your work and want to have same résultat
You Can reply me at this email : samxxs@hotmail.com
Thanks a lot